


Boneship

by idontevenknowugh



Category: Undertale (Video Game)
Genre: Biting, Fontcest, HoneyKetchup, M/M, Mating Cycles/In Heat, Sexual Exhaustion
Language: English
Status: Completed
Published: 2017-02-13
Updated: 2017-02-13
Packaged: 2018-09-24 02:28:45
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,439
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9695687
Author URL: https://archiveofourown.org/users/idontevenknowugh/pseuds/idontevenknowugh
Summary: Catching his breath, Stretch looked around the room. There was a shivering lump on the mattress, which had to be Sans. He could hear heavy breathing and the steady soft creaking of the mattress springs. His soul lurched as a few pieces slipped into place.





	

**Author's Note:**

  * For [Eiznel24](https://archiveofourown.org/users/Eiznel24/gifts).



> Happy Birthday Eiz! I, uh, I made you some smut. I hope you like it! Have a wonderful day. <3 
> 
> Thanks to [Soul](http://archiveofourown.org/users/undertailsoulsex/pseuds/undertailsoulsex) for some confidence boosting and [Queen](http://archiveofourown.org/users/Queen_of_Sintale) for betaing.

“THANK YOU FOR COMING.” Papyrus said, as he led Stretch up the stairs.

“Of course,” Stretch replied, giving his double an easy smile and chuckled. “You guys are like brothers to me.”

“NYEH.” Papyrus laughed once before facing his brother’s door. “HE WON’T LET ME IN, AT ALL. IT’S BEEN TWO DAYS, AND I’M BECOMING CONCERNED. IF HE’S SICK, THEN HE NEEDS SOMEONE TO TAKE CARE OF HIM.”

Stretch eyed the door before knocking. “Hey buddy, how you doing?” He called out. There was a gasp and the sound of Sans shifting on his squeaky mattress in reply.

“You’ve got your bro real worried,” Stretch added. “If you don't open the door, I’m gonna shortcut in.” He glanced over at Papyrus, who gave him a tight smile.

“I- I’m…fine.” Sans finally responded, sounding not at all fine. Stretch frowned.

“Sure, buddy.” He turned to Papyrus, setting a hand on his double’s scapula. “Alright, I’m going in. He’s gonna be okay.”

“THANK YOU,” Papyrus repeated, his smile becoming a bit more relaxed. Stretch just nodded and pulled his arm back. Reality blinked out for a second, then he was in the hot, suffocating darkness of Sans’s room.

A heavy, sickly sweet smell invaded his nose instantly. Stretch recoiled, covering his face with the neckline of his hoodie. The smell made it through, but the barrier helped.

Catching his breath, Stretch looked around the room. There was a shivering lump on the mattress, which had to be Sans. He could hear heavy breathing and the steady soft creaking of the mattress springs. His soul lurched as a few pieces slipped into place.

“Oh shi-” Stretch felt blue magic surround his soul with a ‘ping’, and he fell forward as the gravity shifted. Just as he was bracing himself to hit the wall of Sans’s room, it shifted again, pulling him down into the mattress. He grunted, looking to his left, where Sans was. There were two bright white eyelights watching him intently, and then Sans suddenly lunged forward, straddling him.

“Sans-”’Stretch managed, before his mouth was filled with the other monster’s tongue. The magic appendage energetically writhed and licked its way around. Not a word he would normally use for anything his friend did. Phalanges were gripping his hoodie, and something suspiciously warm and hard was pressing into his pelvis. All of this, combined with the musky smell he now recognized as pheromones, made the situation abundantly clear.

Sans was in heat.

With as gentle a grip as he could manage, Papyrus pushed Sans's shoulders back, separating their skulls. Sans stared down at him hungrily, his tongue hanging out of his mouth. It swiped over his teeth, and Stretch shivered. He regarded Sans for a moment.

A drop of liquid splattered on his cheek bones, followed by a couple more.

“Get…out…,” Sans whispered, brokenly, tears dripping from his sockets. “Before I…hurt you….” The blue magic holding him down suddenly let up. Stretch let go of Sans’s shoulders, and wrapped his arms around him instead. The other skeleton tensed at the touch.

“Go…,” he whined.

“No way,” Stretch replied, smiling. He pulled Sans flush with him. “Leave my friend to suffer alone? No way. I’ll help you through it. I’ll take care of you.”

There was a hitch of breath from Sans, and then his pelvis ground down into Stretch’s. The sweet smell grew stronger, but he didn't try to block it out anymore. Groaning, Stretch felt his magic start to warm, reacting to Sans’s heat by increasing his own sex drive.

With a hum, he buried his face in Sans’s neck and licked at the vertebrae. The skeleton on top of him shuddered. Stretch felt his senses grow hazy, except for where their bodies made contact. The pressure of bones against his own was sharp and intoxicating. He ran his phalanges along Sans in a wild pattern, desperate to feel all of him.

Sans writhed against him, the magic at his pelvis rubbing into Stretch’s until his own magic appeared as the right counterpoint to Sans’s, the soft mound tingling at the friction even through the clothes.

“STRETCH?”

Cursing himself for letting the heat carry him away without reassuring Papyrus, Stretch pulled his skull away with no small amount of reluctance. Sans moved forward to close the gap, but Stretch slapped a hand to his forehead. There was a growl from the other skeleton in response and Stretch felt his pants moisten at the sound.

“Every- uh- everything’s fine,” he called, trying to keep his voice steady. Which became even more difficult as Sans gave up on kissing him and began to wiggle his way down Stretch’s body, rubbing up against him with every movement. Stretch bit down, whining into his teeth.

“ARE YOU SURE? YOU SOUND…DISTRESSED.” Papyrus called through the door hesitantly. Stretch couldn't entirely disagree as his shorts were unbuttoned and yanked down. Still, he lifted his pelvis to allow them to be removed, and Sans wasted no time at all. As soon as they were free, he pressed his face to Stretch’s magic, licking and nipping at the folds of flesh.

“Oh shit!” Stretch arched off the bed, pressing his pelvis into Sans’s face. “I’m sure. He just, ngh, he needs bed rest…haaaaa.” Sans was thrusting his tongue into his pussy aggressively, making Stretch’s hands fly down to rest on his skull. He couldn't bring himself to push the other monster away, instead pressing him deeper.

“I’ll take…care…him,” with the last of his rational thought, Stretch tried to reassure Papyrus. “Don’t…worry…”

If there was a reply, he didn't hear it. The pheromones had done their job, and his world narrowed to Sans and how his tongue seemed to be growing longer, reaching deep into him and moving, hot and wet.

“Fuck,” Stretch clutched at Sans’s skull, pelvis arching up as he gave into the overwhelming need. Sans responded by thrusting his tongue into him almost frantically. Stretch reached his first orgasm gasping, his limbs tensing as pleasure wracked his body.

Sans didn't stop, extending his orgasm and lapping up the result with long, broad strokes of his tongue. Stretch looked down to find that he was looking up at him, the hungry look in his sockets only more intense. A thrill moved through him, his magic aching for more.

“Please…,” he whined, wiggling his pelvis in an attempt to communicate what he couldn't with words. Sans didn't tease him, the heat making him just as desperate, if not more so.

He sat up, Stretch’s long legs over his shoulders, and thrust into him surprisingly slowly for someone two days in and unfulfilled. Any other day, Stretch would have been thankful, not being used to this role. Now, however, he pushed his pelvis into Sans, trying to get him deeper, faster. Sans groaned, his hands tightening around Stretch's femurs.

The next thing Stretch knew, Sans was drawing back out and thrusting with a snap of his pelvis. That was more like it. Stretch moaned and clutched at the bed. His skull tipped back, spine arching, as Sans proceeded to pound into him. It was amazing.

*

Sans was on his back, Stretch slamming down onto him again and again. The feeling of the other monster inside him was intoxicating. Panting with pleasure, exertion, or both Stretch leaned down to kiss Sans, his tongue moving against the other’s messily. Sans responded by thrusting up into Stretch, pressing deeper into him.

*  
Stretch bit down on the pillow as Sans drove into him from behind. The motion rocked his whole body. The clack of bone on bone mingled with Sans’s grunts to make a lewd soundtrack that just made him that much more desperate. With a whine, Stretch pushed back into the thrusts and Sans leaned over him, wrapping an arm around his ribs. The new position had his cock slamming into Stretch at an angle that made him cry in pleasure.

*

Sans bit down on Stretch’s clavicle just enough that it was on the edge of painful. The taller skeleton winced. His own, artificial, heat couldn’t hold out any longer. The haze of pleasure that turned everything Sans did into a burst of arousal was fading. Another round would be painful, not to mention dangerous. Sans, however, still sported an erection. He was reaching for Stretch’s leg, to move it out of the way and continue.

“Shit,” Stretch lunged forward, pushing Sans down and taking the other monster’s cock into his mouth. Sans groaned, his attempt to regain control faltering as his pelvis bucked up, welcoming stimulation, wherever it came from.

As exhausted as he was, Stretch put everything he had left into getting Sans off for what he hoped was the last time. Almost completely spent, the taller skeletons magic finally dissipated from his pelvis.

His tongue wrapped around the magical appendage, sliding up and down. Sans cried out wordlessly at the move, spine arching up off the bed. He was panting and, as intelligent thought returned, Stretch could see that the mindless fucking had taken its toll on him as well.

Streaks of blue and orange sweat coated Sans, and his joints were shaking, even as he responded to the pleasure. His tongue and cock looked dull compared to the brilliant blue they’d been when they started.

More determined than ever to see this end, Stretch took Sans’s member deep into his mouth, using the last of his magic to form a throat, which squeezed his friend’s cock. Sans wailed, and Stretch had to wonder how they’d sounded these past...hours? Days? He honestly wasn't sure.

Drawing his skull back, Stretch drew his tongue along the member, letting it uncoil, and lick along the tip when he reached it. Sans came with a broken gasp, his release shooting up to land mostly on himself, though Stretch wasn’t spared. With a grimace, he wiped some off his skull and found the same blue and orange coat of sweat covered him.

When Sans dropped to the mattress and lay still, Stretch pushed himself up so he could sit on his knees. Crawling to the side of the bed, mindful not to touch the other monster, Stretch gave him a careful look over. His cock was gone, which was good. His heat was over. Sans’s eyelights were also gone, making Stretch’s soul stutter in alarm, but his rib cage was moving up and down raggedly.

Sitting back, Stretch breathed a sigh of relief. Looking around Sans’s room, he found, unsurprisingly, nothing to clean up with. He contemplated teleporting them both to the bathroom, but touching Sans could make his heat flare up again. He couldn’t risk it. Besides, he wasn't sure he actually had the juice to move them anyway.

He went about Sans’s room looking for clean-ish clothing for both of them, even though anything of Sans’s wouldn’t fit him at all. His own clothes were...in desperate need of a wash. He had settled on a set for each when he heard a groan behind him. Turning, he saw Sans sitting up.

“Hey,” he greeted his friend, feeling suddenly awkward. Sans looked over at him, his expression groggy. He spent a minute just staring before he perked up, looking horrified.

“D-did I...fuck!” Sans’s skull dropped into his hands, his frame shaking as he made a broken noise that might have been a sob if his voice hadn’t been worn thin by their activities. Stretch stepped over to him, hands up, even though he wasn’t looking.

“No, no. I mean, you did fuck me, a lot.” He laughed, but Sans just tensed. Cursing his poor choice of words, Stretch keeled down on the mattress. “I stayed by choice. You, somehow, regained control enough to let me go.”

Sans glanced up from his hands, still looking miserable. Stretch gave him a tired smile.

“I chose to stay, to help. Going through a heat alone...it’s pretty awful.” Sans nodded, looking a little more at ease. Stretch continued, “you didn’t do anything that I didn’t sign up for.

“Not like I didn’t enjoy myself.” He added for good measure, and Sans even kind of smiled at that. There was a long pause, but the silence was becoming more comfortable.

Stretch hesitantly broke it. “We should probably go get cleaned up. Your bro is probably pretty worried.”

Sans looked at him, alarmed.

“Oh stars, Papyrus…,” he muttered. “How long has it been?”

“No idea.” Stretch shrugged. “It had been two days by the time I showed up.”

Sans only groaned at that and struggled to his feet. He stared at the door for a moment before turning to Stretch with a wry smile.

“Well, time to face the music.”

Once they took turns slipping out of the room to go shower, Sans and Stretch walked downstairs together, ready to calm a frantic Papyrus.

What they found instead was Papyrus putting the finishing touches on a pot of spaghetti that, to Stretch’s famished soul, smelled heavenly. Papyrus took one look at the them and nodded before turning to serve up two heaping portions.

“Bro, I-,” Sans stepped forward, starting to explain, but Papyrus held up a hand.

“THERE WILL BE TIME TO TALK. RESTORE YOUR MAGIC FIRST.”

They did so. The spaghetti did not taste as good as it smelled, but Stretch cleared his plate anyway, with many praises to the chef. Sans tucked away his fair share, however, he was silent. Once they were stuffed and Papyrus had cleared the table, Sans was treated to a glare.

“WHY DIDN’T YOU COME TO ME?” he asked in his blunt way. “IT BECAME OBVIOUS QUITE QUICKLY WHAT WAS GOING ON ONCE STRETCH WAS IN THERE.”

Sans had no answer, his jaw opening and closing several times as he tried to come up with some kind of response. While he did so, Papyrus turned to Stretch, who flushed.

“THANK YOU FOR TAKING CARE OF HIM.” It wasn’t quite what Stretch had been expecting. He nodded silently. Glancing over at Sans, he found the other skeleton bright blue. At least now Papyrus’s position on the matter was clear. Sans could spend future heats with the monster he’d always wanted to. As Sans walked him down to the basement, Stretch found he could smile easily about how things turned out.

“Hey Stretch,” Sans said, as they got ready to send him home. He had recovered from his unease about the situation and his embarrassment over Papyrus’s clear understanding of their activities. He was smiling at Stretch easily, and it became clear their friendship was not only intact, but stronger. “Thanks.” 


End file.
